Research Of Manufacturing And Bending Process And Parameter Optimization Of Variable-section Rectangular Tube

Rectangular tube parts are a common type of hollow tube in our daily life and production.It is used in many fields,such as automobile,ship,aeronautics and astronautics,construction and petrochemical industry.Variable-section rectangular tube is a kind of special rectangular tube.The variable cross section is his biggest feature and determines the specificity of craft.At present,there are few studies on manufacturing and bending process of variable-section rectangular tubes.Most of the existing processes is to form two pieces of metal plates first and then weld them together.In this way,the stress of the weld is large,it is easy to break and the quality is not guaranteed.In order to solve the problem,the manufacture and bending process of a variable-section rectangular tube are designed with seamless steel tube as raw materia.In view of the manufacturing process of variable-section rectangular tube,the four die radial extrusion forming process is designed in this paper.The general deformation law is simulated from two dimensions,and the influence of the parameters such as the thickness diameter ratio,the friction coefficient and the mold speed on the deformation results is explored.A method of eliminating the concave defects in tube by using the reverse deformation of the die is put forward.For the tube parts with common thickness to diameter ratio,the corresponding optimal die arc degree is obtained through simulation and optimization.After that,the two-dimensional deformation rule is applied to three dimensions,and the defect elimination is successfully realized.Taking a size variable-section rectangular tube as an example,the experiment was carried out.The difference between the forming results of the flat die and the arc die is compared with the simulation results,and the accuracy of the simulation results and the feasibility of the process are verified.Point to the bending process of rectangular tubes,the influence of parameters such as the friction coefficient,the corner radius of the tube and the rotational speed of the bending die on the bending defect was studied.This paper design and improve the traditional rotation bending process,a non mandrel and anti compensation method of bending forming technique is put forward.The simulation results show that this method can effectively eliminate the concave and folding defects.The variable radius bending die was designed.The parameters of the reverse deformation of the rectangular tube were optimized for a variable-section rectangular tube.Take the minimum of internal folding and external depression as the optimization goal,the influence of different parameters on defects is obtained,and two sets of optimal parameters are obtained.Then the comprehensive equilibrium method is used to analyze the two sets of optimal parameters,and a group of optimal process parameters are finally obtained.